Light emitting diodes (LEDs) and organic light emitting diodes (OLEDs) are rapidly replacing existing light sources and are a focus of attention due to outstanding energy efficiency and long lifespan thereof Generally, light emitting diodes form a light emitting diode package together with components such as a reflector, a reflector cup, a scrambler, and a housing so as to maximize optical efficiency through high reflectance. Such components are required to withstand high temperature while minimizing deterioration in reflectance and whiteness due to yellowing.
As engineering plastics, polyester resins, copolymers thereof, and blends thereof exhibit useful properties and are thus used in various fields including interior/exterior materials for products. Particularly, polyester resins are used as a material for such components. Examples of polyester resins mainly used as a material for the components include highly heat-resistant polyester resins. However, highly heat-resistant polyester resins have problems of low crystallization rate, low mechanical strength, and poor impact resistance, although the highly heat-resistant polyester resins do not suffer from deformation at high temperature and exhibit good discoloration resistance.
To overcome these problems, typically, additives such as inorganic fillers have been added to the polyester resins to enhance mechanical strength and impact resistance. However, when an excess of additives such as inorganic fillers is used, there is a concern of deterioration in moldability, such as bleed-out.
A polyester resin composition has been developed wherein a polyolefin copolymer is included in a polyester resin to enhance discoloration resistance and impact resistance. However, such a polyester resin composition also has problems of low crystallization rate, poor moldability and molding stability, and insufficient mechanical properties.
Therefore, there is a need for a thermoplastic resin composition which has excellent mechanical properties in terms of reflectance, reflectance maintenance at high temperature, and flexural strength without suffering the above problems, and can thus be used for components for light emitting diodes.